Payload expulsion system for deep-target penetrators

ABSTRACT

Improved deep target penetrating munitions are disclosed which bring about controlled ejection of the payload following the penetration by the munition of the ceiling of a hardened facility. The ejection results from a plurality of selected propelling charges, which are activated following a signal from a fuze by a shock-hardened electronic trigger system. The shock-hardened electronic trigger system is programmed to automatically select the appropriate charges to match and cancel out the instantaneous terminal velocity of the munitions following the penetration of the ceiling of a hardened target facility. In this manner, the payload is deployed within the target facility for maximum effect and minimum collateral damage.

Priority is claimed Provisional Patent Application 60/554,067, filed on Mar. 18, 2004.

The U.S. Government may have rights in this application under contract No. F0830-02-C-0049 between Veritay Technology, Inc. and the Department of Defense, U.S. Air Force, Munitions Directorate

FIELD OF INVENTION

This invention relates to munitions and more particularly to the deep-target penetrating munitions.

BACKGROUND OF THE INVENTION

Certain future military munitions for penetrating hardened underground facilities carry payloads intended to be ejected immediately after they penetrate the ceiling of the interior of such facilities, but before they reach the floor. Due to inertia, upon entry into the interior the penetrator retains considerable terminal velocity, such that, unless the payload is ejected in the direction opposite the direction of travel of the penetrator at a velocity to cancel the instantaneous velocity of the penetrator, the payload would fail to be deployed where intended in the facility's interior. This could lead to collateral damage and, potentially, to dispersal of toxic materials or agents which may have been stored in the underground facility, instead of their deactivation. Because the terminal velocity of the munition varies, the expulsion velocity has to be adjustable to ensure a correct velocity match. To prevent such undesirable events from occurring, more sophisticated payloads are needed that are at least equally effective as previous munitions but reduce the possibility of collateral damage.

Such improved munitions, in accordance with the present invention, may be suitable among other purposes, for attacking hardened underground facilities, such as command and control centers and biological/chemical warfare production and storage facilities.

These munitions comprise four principal components:

-   -   1) A thick-walled casing capable of withstanding the loads         encountered during hard target penetration,     -   2) A payload of some type to cause the desired effects following         entry into the interior of the facility,     -   3) A smart fuze and a shock-hardened electronic trigger system         to sense entry and initiate the payload expulsion sequence at         the proper time     -   4) Propelling charges to bring about the expulsion of the         payload.

Accordingly, it is a feature of the present invention to provide improved deep-target penetrating munitions to achieve controlled expulsion and deployment of payloads.

SUMMARY OF THE INVENTION

Briefly described, in penetrator munitions according to the invention a payload is ejected from the penetrator munition by an expulsion system, which essentially functions like a gun (with the penetrator's casing acting as the gun barrel) during the time interval while the penetrator munition traverses the interior of the hardened facility. The expulsion occurs through the rear of the penetrator munition. A dedicated fuze is used to time the event of expulsion. The fuze is located in the casing of the penetrator, which also contains the payload. In order to counteract the velocity of the penetrator munition at the instant after it has breached the ceiling of the target facility, the penetrator is equipped with a number of propelling charges of various sizes. These charges are parts of an expulsion system, which, when triggered, drive a piston through the interior of the casing and to cause expulsion of the payload.

In accordance with further features of the invention, the propelling charge of the expulsion system, located in the nose cone of the penetrator, may include a number of separate fractional charges of different sizes. A shock-hardened electronic trigger system (SHETS) of the expulsion system receives the terminal velocity information from the fuze and initiates ignition of selected fractional charges to accomplish the payload expulsion in a controlled manner, including controlling the timing of the ignition of the fractional charges. The best to match the terminal velocity of the penetrator, the selected fractional charges may be ignited simultaneously or in a sequence. Because the penetrator may be damaged while penetrating the ceiling of the target facility, the timing of the expulsion events takes this into account, such that the expulsion occurs at the right time with sufficient, but not excessive, force so as to avoid rupture of the casing of the penetrator.

The expulsion system may provide for igniting any residual fractional propelling charges after a brief delay after the expulsion of the payload is completed. This may be done for safety reasons to eliminate the residual explosives or to inject hot gas into the interior for additional destructive effects.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 schematically illustrates a deep-target penetrator munition embodying an expulsion system provided by the invention. The drawing is a cross-section along the major longitudinal axis thereof.

FIG. 2 is a perspective view schematically illustrating the internal structure of the propellant charge holder in the nose cone of the penetrator munition shown in FIG. 1.

FIG. 3 is a perspective plan view that schematically shows the propellant charge holder within the nose cone of the penetrator munition with the cover plates of the propelling charges removed.

FIG. 4 is a block diagram of the shock-hardened electronic trigger system (SHETS)

DETAILED DESCRIPTION

Referring more particularly to FIG. 1, the front of the nose cone 10 is a hardened, massive part of the penetrator casing. The nose cone contains the propellant charge holder 11, which in turn houses multiple fractional propellant charges 12, 13. Each fractional charge is preferably a granular propellant substance with igniter tubes or channels 19, 20 at the centers of these fractional charges. The granular propellant is consolidated to form rigid propelling charges to fit exactly into the charge cavities within the propellant charge holder 11. Propellant consolidation into rigid structures may be accomplished using a process in which the propellant is coated during the last stage of its manufacture with a special thermoplastic material that becomes soft and sticky at elevated temperature. Consolidation occurs by placing heated propellant into a mold and compressing it axially until the proper compaction density is achieved. The consolidation process compacts and bonds the propellant, thus creating propelling charges with desired geometrical and mechanical properties. The consolidation process described is preferred, since it can result in good mechanical properties, eliminate excessive drying, and is less labor-intensive than other charge consolidation processes. To enhance ignition characteristics, a center cavity may be molded into each propellant charge for placement of ignition booster materials and an electric squib within the igniter tubes 19, 20 to initiate the expulsion event. To assure that the ignition is limited to the designated fractional charges, these charges may be encased in cavities lined with steel (or some other appropriate metal), and with steel or tough polymeric caps placed at the ends to seal off each such cavity. These cavities are not shown to simplify the illustration. The individual fractional charges could also be contained within polymer bags or wrap material (also not shown) to further prevent hot combustion gases from causing inadvertent ignition of the fractional charges that are not being purposefully ignited. The metal-lined cavities, which house the propelling charges can also be additionally lined with inert material, such as an elastomeric polymer or other hydrocarbons based materials, such as asphalt, to both insulate and cushion the explosive charges during the impact and penetration by the munition.

FIGS. 2 and 3 show the placement of the propelling charges 12 and 13, as well as additional charges 21, 22, 24 and 25 from several of which the cover plates have been removed.

While penetrating the hardened structure, the casing may experience some damage, such as bending or flattening, if the penetrator's axis is not aligned with the velocity vector at impact. The combination of expulsion charge pressure level and malleable payload characteristics are tailored to allow the expulsion of the payload to occur reliably, even from a casing that has been damaged.

The greater number of fractional charges used, especially of various sizes as shown in the figures, the greater would be the range of velocity adjustment. The velocity of expulsion can be controlled by firing the selected propelling charges simultaneously or sequentially, as well as by appropriately timing the ignition sequence. Based on the terminal velocity information from the fuze 16, (see FIG. 1) shock-hardened electronic trigger system 30 would automatically select the best firing combination and ignition timing of the propelling charges to achieve the closest velocity match.

The propellant charges:

-   -   Have well-defined defined geometry with respect to the molded         ignition channels (19, 20)     -   Reduce the possibility of the charge break up or premature         ignition due to the high-G impact and penetration into the         target     -   Inhibit early flame spread so as to moderate the rise in         pressure     -   Require minimum space, yet provide maximum energy density     -   Ensure progressive combustion with moderate pressure rise

The penetrator munition may have a payload 15, which may be of the type heretofore used in penetrator munitions (e.g., an explosive or a chemical or biologic suppressor}. The payload 15 may have multiple payload sections containing components designed to produce destruction or damage of the target. When the fuze 16 senses the passage of the munition through the ceiling, signifying entry into a room, a closely-timed sequence of events is initiated by the payload expulsion system to expel the payload 15 from the casing by firing all or some combination of propelling charges 12, 13, and 21, 22, 24, and 25, as discussed above, and to disperse and activate the payload to perform its intended functions. The expulsion charges cause a piston 14 to move through the barrel of the penetrator casing, pushing on the payload 15, which forces out the base plate 17 and the end cap 18 and enters the interior of the target facility. More specifically, the shock-hardened electronic trigger system 30 operates to control the ignition of the charges in a preselected sequence or follows the steps of a control algorithm in response to a signal from the fuze to control the ignition process.

The payload expulsion charge is intended to be capable of performing several functions and adhering to relatively strict functional performance requirements. As the munition is penetrating the targeted underground facility, a window of opportunity opens up immediately after the munition passes through the ceiling and before it reaches the floor or base structure. Depending on the residual entry velocity (in the range of 100 to 850 ft/sec) and the vertical dimension of the underground facility, this time window can typically range from about 10 to more than 100 milliseconds. To match payload expulsion rate with the residual entry velocity, indicated by the smart fuze sensors and controlled by the SHETS 30 thereby canceling it, the payload expulsion system disclosed herein utilizes multiple fractional propelling charges, and piston 14, in effect simulating a gun barrel as described above.

FIG. 4 is a block diagram of SHETS module 30. It comprises one or more shock-hardened electronic trigger systems 31, power capacitors 32 and field effect transistors 33. The shock-hardened electronic trigger systems 31 receive instantaneous velocity data from the fuze 16 and responsive to these data to select the appropriate expulsion charges 19-25 and to control the ignition timing sequence of these charges in accordance with a stored program. The shock-hardened electronic trigger systems 31 actuate the appropriate field effect transistor switches, which in turn fire the expulsion charges 19-25. The power for the SHETS module is provided by the power capacitors 32, which are charged from an external power source only after the munition is dropped from the aircraft. The capacitors are of a size adequate to maintain the necessary voltage level throughout the entire penetration event. 

1. Deep target penetrating munitions comprising a casing having reinforced nose cone, a payload to be ejected, a fuze to initiate the ejection of said payload, including a plurality of propelling charges and means for providing an expulsion system, which effects expulsion of said payload after penetration of and within a hardened target facility.
 2. Munitions according to claim 1 wherein said expulsion system comprises within a hardened target facility, a shock-hardened electronic trigger system to control the sequence of expulsion of said plurality of propelling charges to bring about the ejection of said payload within said target facility.
 3. Munitions according to claim 1 in which said means providing said expulsion system include means operational for effective payload ejection payload ejection upon the penetration by said munitions of a ceiling of said target facility but before said munitions reach a floor of said facility.
 4. Munitions according to claim 1 in which said propelling charges are of different sizes.
 5. Munitions according to claim 2 in which said shock-hardened electronic trigger system is operative to select some of said propelling charges for activation to bring about the ejection of said payload at a velocity that matches and cancels out the instantaneous velocity of said munitions immediately following the penetration by said munitions of said ceiling.
 6. Munitions according to claim 1 in which said propelling charges are selected from the group consisting of said propelling charges of different sizes which are activated simultaneously and of propelling charges which are activated sequentially.
 7. Munitions according to claim 2 in which said shock-hardened electronic trigger system is controlled by said fuze to initiate said expulsion sequence.
 8. Munitions according tor claim 1 in which said propelling charges are of granulated propellant material.
 9. Munitions according to claim 1 in which said propelling charges are compacted.
 10. Munitions according to claim 9 in which a binding agent is included in said compacted charges.
 11. Munitions according to claim 9 in which said propelling charges are of shape selected to facilitate expulsion of said payload
 12. Munitions according to claim 9 in which said propelling charges include voids useful for containing means for igniting said charges.
 13. Munitions according to claim 1 in which said casing has a nose cone and said propelling charges are installed in metal-lined cavities situated in said nose cone.
 14. Munitions according to claim 13 in which said cavities are internally lined with inert material.
 15. Munitions according to claim 9 in which said compacted propelling charges are encased in polymeric materials.
 16. Munitions according to claim 1 in which said expulsion system includes means for igniting at least one of said propelling charges following said ejection of said payload.
 17. Munitions according to claim 1 in which said propelling charges are selected from the group including charges which are stick, monolithic, and perforated propellant charges.
 18. Munitions according to claim 2 in which charges are ignited in sequence and said shock-hardened electronic trigger system controls the timing of said ignition sequence of said propelling charges.
 19. Munitions according to claim 2 in which said shock-hardened electronic trigger system comprises one or more microprocessors, a plurality of field effect transistor switches, and one or more power capacitors.
 20. Munitions according to claim 19 in which said power capacitors provide electrical power to the electronic components of said shock-hardened electronic trigger module.
 21. Munitions according to claim 20 in which said power capacitors are charged only following the release of said munitions from an aircraft.
 22. Munitions according to claim 19 in which said field effect transistor switches responsive to signals from said microprocessors initiate the ignition of said expulsion charges. 